Diversity of vehicles, such as fuel cell vehicles and hydrogen vehicles, have been developed to be equipped with a high-pressure gas tank for storing a high-pressure gas, such as compressed hydrogen, and to be driven with the high-pressure gas stored in the high-pressure gas tank as a fuel gas.
A valve apparatus is generally connected to the high-pressure gas tank for storing the high-pressure gas (compressed gas or liquefied gas) to discharge the high-pressure gas from inside to outside of the high-pressure gas tank and to fill the high-pressure gas from outside to inside of the high-pressure gas tank. A safety valve device is typically connected with the valve apparatus to discharge the high-pressure gas stored in the high-pressure gas tank to the outside in response to a temperature increase of the high-pressure gas tank to or above a preset reference temperature due to, for example, a fire, and thereby prevent an excessive increase of the internal pressure of the high-pressure gas tank.
Various techniques have been proposed for the high-pressure gas tank equipped with such a safety valve device. For example, a technique disclosed in Japanese Patent Laid-Open No. 2007-106262 discharges a gas fuel (high-pressure gas) downward in a vertical direction from a gas fuel tank (high-pressure gas tank) mounted on a vehicle. Other relevant techniques known in the art include Japanese Patent Laid-Open No. 2000-193249, No. H06-165803, No. 2002-168399, and No. 2004-263786.
In a typical application of the high-pressure gas tank with the safety valve device mounted on a vehicle, in conformity with the regulation by the law, the design of the safety valve device is required to prohibit discharge of the high-pressure gas in a forward direction of the vehicle in an active state of the safety valve device. The technique disclosed in Japanese Patent Laid-Open No. 2007-106262, however, may cause the high-pressure gas to be discharged in the forward direction of the vehicle in the active state of the safety valve device. As explained above, the technique disclosed in Japanese Patent Laid-Open No. 2007-106262 discharges the high-pressure gas downward in the vertical direction in the active state of the safety valve device. When the vehicle runs on a down slope, this means that the high-pressure gas is discharged in the forward direction of the vehicle. When this prior art safety valve device is activated in an overturned attitude of the vehicle, the vertically downward discharge causes the high-pressure gas to be released toward the vehicle body. This may expose the driver and the passengers of the overturned vehicle to danger. Namely the technique disclosed in Japanese Patent Laid-Open No. 2007-106262 is not capable of adequately adjusting the discharge direction of the high-pressure gas in the active state of the safety valve device.